This invention relates to an improved pressure vessel of the type used to contain high pressure fluids.
Particularly in transportation systems such as aircraft, fluid pressure vessels are used to store air or other fluids to provide energy for emergency operation of hydraulic structures such as actuators. Because such systems find their use primarily in emergency situations, they must be fail safe. Accordingly, they must often be checked for structural integrity and freedom from corrosion.
The above-described air reservoirs are customarily made of heat-treatable steel with a wire over-wrap made of the same material. Such reservoirs or "gas bottles" have a limited life of only about fifteen years and, particularly because of the wire over-wrap are subject to corrosion problems. To fight the corrosion problems the bottles must be removed from the aircraft or other vehicle for regular maintenance. In the case of wire-wrap bottles it is necessary to strip off the wire; treat the bottle for corrosion; inspect the bottle for structural integrity; rewrap the bottle; and, test it prior to its return to the aircraft or other vehicle. Because this is an expensive and time consuming process, it is an object of this invention to provide such a pressure vessel that is more easily maintained and will meet the stringent specifications without requiring a wire wrapping.
Because safety is such an important factor--particularly in transportation vehicles--a substantial advantage of the invention is the provision of a more safe pressure vessel. In this respect, the above-discussed wire wrapping is used to reduce shattering of such gas bottles if they are struck such as by gun fire during operation. The vessel and method of the invention provide a structure that does not shatter when subjected to conventional gunfire tests and the vessels of the invention have an "infinite life".
Other advantages of the invention are that no resin coating is required; the vessels of the invention are non-magnetic even after 60% cold working; there is no significant growth in bottle size after pressure cycling; there is no leakage even at extreme temperatures; the vessel can withstand the extreme temperatures of altitude and even cryogenic temperatures; the fabrication method does not significantly affect the physical properties of the material from which the vessels are constructed; and the vessels meet conventional aircraft weight requirements.